The interaction of sulfur containing ligands with species containing the structural unit Mo2 4 ion is being investigated, searching for strongly reducing species. Thioethers coordinate to MO2 4 ion without rupturing the MO-MO bond. The thioethers are replaced by a dithiol and the resulting material is strongly reducing, so strongly reducing that it appears to reduce every solvent so far used. An immediate goal is to find a solvent which does not oxidize it, and then to investigate the reactions with oxidizing agents such as dinitrogen and acetylene. Other work is directed toward preparing a complex of composition (Cl5OsN2OsCl5)4- in the hope that with it, spontaneous rupture of the bond in the briding dinitrogen will be realized, producing the known species (OsClsN)2- as product. This would in effect represent a 6e-reduction of great novelty and significance. Progress is being made in the basic coordination chemistry (preparations and characterizations) of osmium relevant to the stated goal.